As an antenna device for a portable telephone, such a type is known that includes a whip antenna consisting of a conductive wire like a resilient rod, and a helical antenna consisting of a conductive wire having a helical shape and connected to the top of the whip antenna. The whip and helical antennas are coated with layers each made of a synthetic resin (the term "a resin" used hereinafter means a synthetic resin) to improve their appearance and to protect their bodies. The whip antenna is provided with a first male terminal electrically connected thereto on the bottom side, and a second male terminal electrically connected to the helical antenna on the top side. There are two cases, in one of which the helical antenna is electrically connected to the whip antenna, and in the other of which the helical antenna is electrically isolated from the whip antenna. When the antenna device is pulled out of the telephone main body, the first male terminal is electrically connected to a female terminal arranged on the telephone main body. When the antenna device is pushed into the telephone main body, the second male terminal is electrically connected to the female terminal arranged on the telephone main body.
The whip antenna coated with a resin layer needs to have an exposed portion uncovered with the resin layer at one or two ends to attach a male terminal or terminals to the whip antenna. Conventionally, such a whip antenna coated with a resin layer is manufactured by either of the following two methods.
(1) A whip antenna having a predetermined length is inserted in a resin tube which has been cut in advance to have a slightly shorter length. PA1 (2) A long metal wire for a whip antenna is coated with a resin extrusion-molded all over the wire, and then is cut into a predetermined length, from which portions of the resin coating layer at opposite ends are peeled off. PA1 a whip antenna (1) having a larger-diameter portion (52) formed near its upper end by means of forming; PA1 a first coating layer (19) consisting essentially of a synthetic resin, and having a main portion (54) coating the whip antenna (1) below the larger-diameter portion (52), and a joint portion (56) coating the larger-diameter portion (52); PA1 a metal terminal (62) mechanically connected to the joint portion (56); PA1 a helical antenna (25) mechanically connected to the whip antenna (1) through the joint portion (56) and the metal terminal (62), such that the helical antenna (25) is electrically connected to the metal terminal (62) and electrically isolated from the whip antenna (1); and PA1 a second coating layer (31) consisting essentially of a synthetic resin and coating the helical antenna (25). PA1 a whip antenna (1) having a larger-diameter portion (52) formed near its upper end by means of forming; PA1 a guide ring (7) consisting essentially of a synthetic resin and fitting on the whip antenna (1), such that the guide ring (7) abuts against the larger-diameter portion (52) to rest at a position below the larger-diameter portion (52); PA1 a first coating layer (19) consisting essentially of a synthetic resin, and having a main portion (54) coating the whip antenna (1) below the guide ring (7), and a joint portion (56) coating the guide ring (7) and the larger-diameter portion (52); PA1 a metal terminal (62) mechanically connected to the joint portion (56); PA1 a helical antenna (25) mechanically connected to the whip antenna (1) through the joint portion (56) and the metal terminal (62), such that the helical antenna (25) is electrically connected to the metal terminal (62); and PA1 a second coating layer (31) consisting essentially of a synthetic resin and coating the helical antenna (25). PA1 a whip antenna (1), PA1 a guide ring (7) consisting essentially of a synthetic resin and fitting on the whip antenna (1) near its upper end, PA1 a first coating layer (19) consisting essentially of a synthetic resin, and having a main portion coating the whip antenna (1) below the guide ring (7), PA1 a helical antenna (25) mechanically connected to the whip antenna (1) through a metal terminal (27), such that the helical antenna (25) is electrically connected to the metal terminal (27) and is positioned on an upper side of the whip antenna (1), and PA1 a second coating layer (31) consisting essentially of a synthetic resin and coating the helical antenna (25), PA1 the method comprising: PA1 a first molding step of molding the guide ring (7) by means of insert molding, using first synthetic resin, such that the guide ring (7) fits on the whip antenna (1) near its lower end, the whip antenna (1) having the larger-diameter portion (52) formed thereon; PA1 a placing step, after the first molding step, of placing in a mold (9) the whip antenna (1) with the guide ring (7) attached thereto, the helical antenna (25), and the metal terminal (62), in accordance with positional relationships in the device; and PA1 a second molding step, after the placing step, of pressure injecting a second synthetic resin different from the first synthetic resin into the mold (9), and coating the whip antenna (1) and the guide ring (7) with the second synthetic resin to form the first coating layer (19), while moving the guide ring (7) on the whip antenna (1) by the second synthetic resin until the guide ring (7) hits the larger-diameter portion (52).
Where the manufacturing method (1) is used, there is a problem in that the resin tube and the whip antenna are less integrated, thereby allowing a positional shift between these two members. If the clearance between the resin tube and the whip antenna is made small to increase their integration, the operation of inserting the whip antenna into the resin tube becomes difficult, and thus the manufacturing becomes difficult to perform automatically.
Where the manufacturing method (2) is used, the operation of peeling off the opposite end portions of the resin coating layer is complicated, so the manufacturing cost becomes high. Further, where the whip antenna, which is generally formed of a thin metal wire, is set within a mold, and a conventional resin molding is carried out, the whip antenna is bent by the resin pressure, so the resin coating layer tends to have an uneven thickness. Especially, the whip antenna needs to have resilience as a property, and thus may be formed of a super-elastic alloy wire, which is flexible and resilient. In this case, the super-elastic alloy wire is easily bent by the resin pressure, thereby hardly forming a resin coating layer having a uniform thickness.
Further, in the conventional manufacturing methods, since male terminals are attached after the resin coating layer is arranged, there are problems in that the male terminals damage the resin coating layer when they are caulked on the resin coating layer, and the male terminals apply an excessive clamping stress to the resin coating layer, thereby causing the coating layer to be split during its service time.